74501. A single layer air cored coil has n turns and inductance L. If a new coil is formed by having 2n turns while keeping the coil length and diameter the same, the new inductance is
74502. The colour code on a carbon resistor is yellow-violet-orange. The value of resistance is
74503. A dielectric of relative permittivity ∈r is subjected to a homogeneous electric field E. The dipole moment P per unit volume is given by
74504. Which of these has the highest dielectric strength?
74505. An electron in a metal suffers collision and if the probability of it being scattered over an angle dθ is 2p P(θ) sin θ dθ where P(θ) is an arbitrary function of scattering angle θ, then
74506. For an insulating material, dielectric strength and dielectric losses should be
74507. Consider the following statements An iron cored choke is non linear and passive device.A carbon resistor kept in sunlight is a time invariant and passive device.A dry cell is a time varying and active device.An air capacitor is time invariant and passive device. Of these statements
74508. Some ceramic materials become superconducting
74509. Assertion (A): Doping level in extrinsic semiconductors is very small.Reason (R): Additional of impurity in the ratio of 1 part in 108 parts increases the number of charge carriers by about 20.
74510. The core of an atom consists of
74511. Assertion (A): Copper is a good conductor of electricity.Reason (R): Copper has a face centred cubic lattice.
74512. When a dielectric is subjected to an electric field E, each volume element of dielectric can be considered to be carrying an electric dipole moment.
74513. Assertion (A): In an intrinsic semiconductor J = (μn x μp)eni.Reason (R): Intrinsic charge concentration ni at temperature T is given by ni2 = A0 T3 e-EG0/kT.
74514. When the atom of rare gas is placed in an electric field the nucleus shifts from the centre of electron cloud by an amount x. If the radius of electron cloud is R, then
74515. Macroscopic quantities of a given material
74516. For a superconductor, the relative permeability is
74517. The relative permeability of a ferromagnetic material is
74518. Assertion (A): The equation D = ∈0∈rE is applicable only to isotropic materials.Reason (R): In polycrystalline materials, the directional effects are absent.
74519. Assertion (A): For a dielectric, P = ∈0(∈r - 1) E.Reason (R): Dipole moment per unit volume is called polarization of dielectric.
74520. Assertion (A): Ferrites are very useful at very high frequencies.Reason (R): Ferrites have high permeability and high resistivity.
74521. In a conductor the current flow is due to
74522. When an electron moves at velocity v in combined electric and magnetic fields E and H, the Lorentz force F is F = - e(E + v x B).
74523. When Schrodinger equation is applied to the motion of electron in the field of protons, the physically acceptable solutions for the wave function exist for quantum number which are
74524. For dielectrics in alternating field, polarizability a e is a complex quantity. The imaginary part of a e is zero for
74525. In the wave mechanical theory, the maximum of the charge distribution in the ground state occurs for a distance from the nucleus equal to